Cognizant Technology Solutions — Unable to access one cognizant portal and recruiter number is not reachable

Address: Hyderabad

Hi, I was offered a position with cognizant and received my offer letter and pre joining formalities email. But I'm unable to open one cognizant portal (blank page is displaying) to accept the offer or to upload other required documents. I drafted a mail to support team but there is no response from them. I tried to contact my recruiter but getting his number is switched off from past 4 days. Im in a confusion that is it good to resign from current organization or not? Please guide me whom should I approach to get my issue resolved.

Thanks in advance.